Switching mechanism for vacuum tubes and the like



July 17, 1923- .1,462,057

P. l. WOLD SWITCHING MEGHANISM FOR VACUUM TUBES AND THE LIKE Filed Sep'. 127.` 1920 'vvenor: Paferl WO/a y Patented July 17, 1923.

yUNITED STATES PATENT OFFICE.

PETER I. WOLD, OF EAST ORANGE, NEW JERSEY, ASSIGNOR 'T0 WESTERN ELECTRIC COMPANY, INCORPORATED, F NEW YORK, N. Y., A CORPORATION 0F NEW YORK.

SWITCHING- MECHANISM FOR VACUUM TUBES AND THE LIKE.

Application led September 27, 1920. Serial No. 413,097.

To all whom it may concern.'

Be it known that I, PETER IRVING VVOLD, a citizen of the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Switching Mechanism for Vacuum Tubes and the like, of which the following is a full, clear, concise, and exact description.

l0 In certain electrical circuits in which it is desirable to maintain continuous action it frequently occurs that a piece or pieces of apparatus may be included which are subject to deterioration of one kind or another, in which case it is necessary to replace the deteriorated element by another. Sometimes this deterioration may amount to a complete and sudden deterioration of the element rendering it totally useless, and at other times the deterioration may be a gradual one in which, after a certain stage has been reached, it would be desirable to replace it'by a new element. With such circuits it is ordinarily necessary to maintain a continuous supervision over the elements inorder to replace them at the proper time.

This invention relates to a means for the replacement of a piece of apparatus subject to such deterioration by another piece of the same character to insure continuous operation. One of its objects is to make the action automatic, such that the replacement will occur whenever the element falls below a certain standard of operation. More specically the invention relates to and has as its object the provision of means for replacing a vacuum tube of the thermionic type 1n an if an when the tube has deteriorated below a certain standard.

In the case of vacuum tubes used as amplifiers or as detectors in various types of electrical circuits, the deterioration may be due to any one of a number of factors, but

probably the most important one is the prac* tical destruction of the element due to the burning out of the ilament, and unless an attendant is present at the time or is called by some signal there may be a serious interruption in the service which the electri cal circuit is intended to give.

The invention will Jbe better understood by reference to the accompanying drawings in which Figure 1 shows a circuit arranged for carrying out the purpose of the invencircuit in which it may be contained,'

tion. Figure 2 shows a modification of the circuit.

Referring more specifically to Figure 1 there is shown a circuit which might well be that of a standard telephone repeater with input terminals at 1 and output terminals at 2, to which latter may be connected any suitable output circuit 3. These linput and output terminals are connected, to the corresponding terminals of a vacuum tube repeater 4, this member comprising an evacuated vessel enclosing a heated filament 5, an anode 6 and a grid 7. The vacuum tube is connected to the circuit as a whole through the intermediary of a multiple switch consisting of four movable members, G, F F2 and P. These are connected together by the memberS, preferably of insulating material, so as to form Vthe multiple switch. These four movable strips are adapted to make contact with either of a group of terminals 10, 11, 12, and 13, or 20, 21, 22 and 23. The first group of these terminals are connected in the order given'to the grid 7, the terminals of the filament 5 and the plate 6 of of the vacuum tube 4.

The movable member G of the switch is permanently connected to one of the input terminals of the line and the member F, is connected to the other input terminal and also to one pole of the filament heating battery A. The member F2 is connected to the other pole of the heating battery A and also to the negative terminal of the plate battery B, which in turn is connected to one of the terminals of the output circuit. The member P is connected through the magnetic coil 14 to the other terminal of the output circuit. The element 8 carries at one end an armature 15 and the electromagnet 14 is so placed with respect to the armature 15, that, with the proper current flowing therethrough it will hold the switch in the operative position shown.

lVith the circuit as thus connected, the

filament 5 will be heated by the battery A and the output circuit will be supplied with voltage by the battery B. The normal space current, which will then be flowing through the tube, will pass through the coil 14 which is so adjusted as to sensitivity that it is able, with the normal space current, to hold the switch in the position shown.

A second vacuum tube 24 is used as a su plementary tube to be used in case the tu e set of contacts to the second set, the tube 24 will occupy exactly the same position with respect to the circuit as a whole as the tube 4 originally did.

A spring 30 is connected to the switch tending to carry it into contact with the second set of contacts, but the switch is normally held in contact with the first set by the Space currentfiowing through the coil 14. If, however, a decrease in the space current vfiowing through 4the tube 4 occurs, the switch will be released when the current falls below a certain predetermined value, and will, therefore, eliminate from the circuit the tube 4 and substitute in -its place the tube 24. Upon this substitution the normal current will again be restored to the cir-- cuit as a whole and in particular to the coil 14, but the adjustment of the sensitivity of the coil can be so arranged that it will not be able now to restore the switch to its former position, mainly because of the increased distance between the coil 14 and the armature 15. In order to avoid any possibility of trouble in this direction, however, it will in general be desirable to have some locking arrangement .by which the switch will be locked up in its second position and such a mechanismis shown at 31.

Figure 2 shows a modification of the circuit. This circuit differs from the first only in a simplification of the switchfwhich in this latter case contains three movable switch members and corresponding contacts instead of four. The terminals ofthe filaments 5 y and 25, which in Figure 1, were shown as going to the contacts 11 and 21 respectively are joined together and connected permanently to one po e of the heating battery A, and the moyablemember F,l of the switch is eliminated. Aside from this feature the circuit arrangement and the operation is the same as that described in connection with Figure 1. y

With the arrangement as set forth, it will ,j not be necessary to maintain a close superlatter condition exists,

vision of the electrical circuit sofar as the deteriorating elements are concerned and an occasional visit will show whether the first or second tube is in operation. I'n case the the supervisor may, at his leisure, replace the first tube by a new one, and may then operate the switch to bring it into its normal position, placing the new tube in operation. The second tube, therefore, acts continuously in the capacity of a supplementary tube to be used in emergencies. In case it is desired a supplementary circuit may be supplied which upon operation of the switch to throw in the second tube will be closed to operate a visual or audible signal, thus attracting the attention of the supervisor.

During operation of the circuit there will. of course. be fluctuations in the space current due to the signal or other impulses impressed on the tube. Obviously the switch should be adjusted as to speed of action and sensitivity so as not to operate under such fluctuations.

While this circuit has been described and explained as being adapted to take care of a change in the characteristics of the vacuum tube which shows itself as a decrease in the space current, it can be adapted to take care of any exceptional change whether it be an increase or a decrease in the space current, and whether this change be due to one cause or another, by arranging the switch to act on an underload or an overload.

Also while the invention has been dcscribed in connection with one form of an amplifier circuit, it is to be understood that it is not limited to this specific disclosure, but may be used with any vacuum tube circuit whether the said tube is used for an amplifier, or a detector, or for other purposes, the principle involved in each case being that, upon the deterioration of one tube, there shall be an automatic cutting out of this tube and the substitution of a supplementary tube. Also, it is to be noted that while the invention has been described in connection with vacuum tubes, that the same principle may be used in connection with a large variety of other types of apparatus.

What is claimed is:

1. An electricalcircuit comprising a. vacuum tube element having an anode and a. cathode, a second element of the same character, means for supplying space current to said first tube, means for supplying heating current to the filament of said first tube, and means responsive to the deterioration of said first tube for replacing said first tube with said second tube and to connect both of said supply means thereto.

2. he combination of elements recited in claim l characterized further by the fact that connections are provided whereby the means for substitutin one tube for the other is operated by t e space current flowing through the vacuum tube.

3. An electrical circuit comprising a Vacuum tube element, a second element of the same character, a source of space current for said elements, a switch mechanism normally holding the first vacuum tube in operational action, and means'comprising a. magnet coil i contact with the grou carrying the space current flowing through the lirst, tube and associated with said switch for replacing the first tu'be by the second when the first tube has fallen below a certain standard.

4. The combination of elements recited in claim 3 characterized further by the fact that upon operation of rthe switch to substitute the second tube for the first, means are provided for locking it up in its second position.

5. The combination set forth in claim 3 and further characterized by the fact that the switch upon operation to substitute the second for the first tube, means are provided for locking it up in its second position.

6.. A vacuum tube circuit adapted to receive incoming impulses and to transmit outgoing impulses, a. three electrode vacuum tube element, a switching mechanism having a. group of terminals to which the terminals of the said vacuum tube are connected, a plurality of contact elements on said switch, means for normally holding said elements in of terminals, a supplementaryl group o terminals, a second vacuum tube having its terminals connected to said supplementary group of terminals and means for automatically moving the contact elements from the first group to the supplementary group of terminals when the first tube has deteriorated below a certain standard.

7. The combination of elements recited in claim 6 characterized Jfurther by the fact that the means for moving the contact elements consists of a magnet coil.

8. The combination recited in claim 7 further characterized by the fact that connections are provided whereby the magnet coil normally carries the space current from the rst tube and is so adjusted that when this current alls below a predetermined value the switch is operated to substitute the second tube for the first.

9. The combination recited in claim 8 further characterized by the presence of a locking mechanism adapted to lock up the switch when it has moved to its second position.

10. The combination set forth in claim 6 further characterized by 'the fact that the two groups of terminals have three contacts each, those in the first group being connected respectively to the id, one terminal of the filament, and the p ate of the first vacuum tube,` those in the second group being similarly connected to the terminals of the second tube.

In witness whereof, I hereunto subscribe my name this 13th day of September, A. D.7

. PETER I. WOLD.. 

